<template>
    <div class="count-box">
        <button @click="handleSub" class="minus">-</button>
        <input @change="handleChange" :value="value" class="inp" type="text">
        <button @click="handleAdd" class="add">+</button>
    </div>
</template>

<script>
export default {
    props: {
        value: {
            type: Number,
            default: 1
        }
    },
    methods: {
        handleSub () {
            if (this.value <= 1) {
                return
            }
            this.$emit('input', this.value - 1)
        },
        handleAdd () {
            this.$emit('input', this.value + 1)
        },
        handleChange (e) {
            const num = +e.target.value
            // 输入不合法的数值或者输入负值，回退成原来的value值
            if (isNaN(num) || num < 1) {
                e.target.value = this.value
                return
            }
            this.$emit('input', num)
        }
    }
}
</script>

<style lang="less" scoped>
.count-box {
    width: 110px;
    display: flex;
    .add, .minus {
        width: 30px;
        height: 30px;
        outline: none;
        border: none;
        background-color: #efefef;
    }
    .inp {
        width: 40px;
        height: 30px;
        outline: none;
        border: none;
        margin: 0 5px;
        background-color: #efefef;
        text-align: center;
    }
}
</style>
